Mr Fraser, the Liberal PM between 1975 and 1983, had warned that Australians working at the US-run Joint Defence Facility at Pine Gap – the intelligence-gathering base which reportedly now plays a key role in locating drone targets - did not have the same legal protection as their US counterparts.

"The purposes for which drones are used are going to be outlawed at some point by international agreement, and the Americans might believe that Americans involved in those programs are given legal cover under the War Powers Resolution passed after 9/11," he said.

"[It] gives totally unlimited power, no geographic limits, no time limits, using any means available or that might become available to an American president to do so.

"But that resolution gives no legal cover to Australians operating out of Pine Gap who are complicit in finding, identifying, locating the so-called target."

But Mr Swinsburg says that is not the case.

"To distil this down to an [Australian] corporal in Pine Gap being put on war crimes [charges] because of an intercept that he or she processed, and [which] is now somehow the executive authority for weapon release, is a little far-fetched, and shows the lack of regard Fraser holds [for] the general public in trying to create a situation when nothing exists," he said.

Mr Swinsburg, formerly a military targeting specialist, served in Iraq and Afghanistan.

Last year, leaks from US intelligence contractor-turned-whistleblower Edward Snowden revealed the facility was part of the XKeyscore program, a controversial computer system that searches and analyses vast amounts of internet data.

In July 2013, Fairfax Media reported claims by former Pine Gap personnel that the base also played a key role in US drone strikes involving the "targeted killing" of Al Qaeda and Taliban leaders.

"The [Taliban] know we're listening, but they still have to use radios and phones to conduct their operations. They can't avoid that," one former Pine Gap operator told Fairfax Media.

"We track them, we combine the signals intelligence with imagery, and once we've passed the geolocation [intelligence] on, our job is done.

"When drones do their job, we don't need to track that target any more."

Mr Swinsburg argues the process is much more complicated.

"If Pine Gap is providing information to a higher-level targeting process, then this information would be fused with reports from many other facilities and agencies to complete an intelligence picture," he said.

"I don't see how a single individual or facility could be singled out for legal prosecution when the targeting process is multi-step ... conducted often over a long period of time with many hundreds of people involved.

"And I suspect a decision to engage targets in another country is not done from personnel at the Pine Gap facility, but somewhere else," he added.

America’s new drone war

Pine Gap has come under greater scrutiny as America's ground wars in Iraq and Afghanistan have wound down and the Obama administration escalates the drone campaign.

This highly controversial, yet largely covert conflict is being waged in the skies of Afghanistan and Iraq, and also over territory where the US is not involved in a declared war; Pakistan, Somalia and Yemen.

In May 2013, US president Barack Obama promised an end to "the perpetual war" by refining and limiting his drone policy, announcing that strikes would only target militants representing a "continuing and imminent threat to the American people" and that no attack would be approved unless there was "near certainty that no civilians will be killed or injured".

Mr Swinsburg, who served as a targeting adviser in the US-led Coalition headquarters during the 2003 invasion of Iraq, says there are "robust" rules of engagement designed to minimise "collateral" civilian casualties.

He contends that drones or Unmanned Aerial Vehicles (UAVs) are preferable to the alternative.

"Prior to UAVs we had cruise missiles. Now the delivery system of choice is the UAV, as they are more flexible and take less time to direct to a target, with much lower collateral damage," he said.

"But with a cruise missile they are 'fire and forget'. At least with a UAV there is a human in the loop up until such time as the trigger is pulled.

"I suspect that the imagery of drone strikes is being milked as much as possible to imply some form of detached 'targeting' process that somehow does not have the rules of engagement applied.

"People somehow believe that these machines have a mind of their own, simply programmed to exterminate all targets without human oversight."

Australians killed in Yemen drone strike

While the politics of this highly contentious form of remote warfare has engulfed Washington, there has been remarkably little public debate in Australia, despite recent revelations Australians had joined the growing casualty list.

'Bin John' was a dual New Zealand national who, according to prime minister John Key, had been in Yemen for "quite some time" and had attended a terrorist training camp.

The Australian and New Zealand governments would not confirm that drones were used in the attack, nor have they subsequently produced evidence the men killed were Al Qaeda members or engaged in terrorist activities.

Mr Fraser claimed disturbing linkages were clearly evident. On April 17 he tweeted: "US murders two Australians in drone strike in Yemen, through Pine Gap Australia complicit in the program. Barbarous."

Mr Swinsburg is confident those killed in the drone strike would have been positively identified – and declared a target of "military necessity".

He is dismissive of claims of Australian culpability.

"I doubt if Malcolm Fraser, when he was PM, was involved in the modern targeting process - which General (Stanley) McChrystal (commander of US Forces in Afghanistan 2008-09 and commander of US Special Operations 2003-08) was very prescriptive in putting in place - a series of critical oversight procedures to ensure that only heavily vetted targets would be engaged," he said.

"I suspect also, noting the media attention on drone strikes, that this attack would have had a high level of Pentagon approval as well.

"And if not, then the commander, and the commander alone, will answer for it. But the fact that the information came from an Aussie in a shared facility (Pine Gap) with shared information, (and who) is now somehow responsible for the commander's decision, is ridiculous."

'The Kill Chain'

The Australian Defence Force operates only unarmed surveillance drones, but senior Australian officers have previously been directly involved in approving missile attacks by armed US drones, in a process unofficially dubbed "The Kill Chain".

In 2012, military sources told the ABC the Dubai-based, two-star major-general commanding Australian forces in the Middle East had directly ordered US drone strikes against insurgents fighting Australian special forces in Afghanistan.

Advising the Australian general in "The Kill Chain" was a military lawyer specialising in the laws of armed conflict.

Mr Swinsburg says it is important to distinguish between these types of attacks - termed "immediate, close-air support missions" - and what is called the "deliberate target process" - when drones attack specific individuals on Washington’s terrorism hit list.

"This is often a very lengthy process that involved many agencies and could take weeks to months or even years to fully prosecute," he said.

"The authority for weapon release/engagement for this is often held at a very high level with a deliberate approval process involved."

Defence denies 'deliberate targeting' of individuals

The Australian Defence Force remains opaque on the exact role played by Pine Gap, and the Australians employed there.

In an email response to a series of questions from the ABC, a spokesperson would only confirm that "the Joint Defence Facility contributes to the intelligence collection capabilities of both countries, providing Australia priority intelligence on issues such as the proliferation of weapons of mass destruction".

However, Defence does offer some detail on the role of Australian drones in Afghanistan.

"The Heron is a remotely piloted, unarmed, intelligence, surveillance and reconnaissance (ISR) aircraft. It currently operates from Kandahar Air Field.

"The aircraft is operated by a task unit comprised of specialists from all three services, although predominately Air Force.

"The Heron Remotely Piloted Aircraft mission in Afghanistan will conclude in July 2014."

Defence confirms armed American or British drones have been used to support Australian troops, saying "Armed Coalition UAS have been part of the suite of options available to support Australian Defence Force operations in Afghanistan" but denies the two-star general commanding the Australian Joint Task Force had ever been involved in "deliberate targeting" of individuals in Afghanistan, Pakistan, Iraq Somalia or the Persian Gulf.

Defence says no Australian officers serve on exchange with US or British units operating "armed Unmanned Aerial Systems" such as Reaper and Predator.

But a spokesperson says "ADF personnel supporting operations in Afghanistan can be involved in targeting processes, however it should be noted that the targeting process is usually independent of the weapons platform selected to conduct a mission".

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